Application Report SLOA058– November 2000 A Single-Supply Op-Amp Circuit Collection Bruce Carter Op-Amp Applications, High Performance Linear Products One of the biggest problems for designers of op-amp circuitry arises when the circuit must be operated from a single supply, rather than ±15 V. This application note provides working circuit examples. Contents 1 Introduction ................................................................................................................................... 3 1.1 Split Supply vs Single Supply.................................................................................................... 3 1.2 Virtual Ground........................................................................................................................... 4 1.3 AC-Coupling ............................................................................................................................. 4 1.4 Combining Op-Amp Stages ...................................................................................................... 5 1.5 Selecting Resistor and Capacitor Values .................................................................................. 5 2 Basic Circuits ................................................................................................................................ 5 2.1 Gain.......................................................................................................................................... 5 2.2 Attenuation ............................................................................................................................... 6 2.3 Summing .................................................................................................................................. 9 2.4 Difference Amplifier .................................................................................................................. 9 2.5 Simulated Inductor.................................................................................................................... 9 2.6 Instrumentation Amplifiers ...................................................................................................... 10 3 Filter Circuits ............................................................................................................................... 12 3.1 Single Pole Circuits................................................................................................................. 13 3.1.1 Low Pass Filter Circuits .............................................................................................................13 3.1.2 High Pass Filter Circuits.............................................................................................................13 3.1.3 All-Pass Filter ............................................................................................................................14 3.2 Double-Pole Circuits ............................................................................................................... 15 3.2.1 Sallen-Key.................................................................................................................................15 3.2.2 Multiple Feedback (MFB)...........................................................................................................16 3.2.3 Twin T .......................................................................................................................................17 3.2.4 Fliege ........................................................................................................................................20 3.2.5 Akerberg-Mossberg Filter ..........................................................................................................22 3.2.6 BiQuad......................................................................................................................................24 3.2.7 State Variable............................................................................................................................25 4 References................................................................................................................................... 25 Appendix A – Standard Resistor and Capacitor Values ................................................................. 26 Figures 1 Split Supply (L) vs Single Supply (R) Circuits ..................................................................................3 2 Single-Supply Operation at Vcc/2....................................................................................................4 3 AC-Coupled Gain Stages ................................................................................................................6 4 Traditional Inverting Attenuation With an Op Amp ...........................................................................6 5 Inverting Attenuation Circuit ............................................................................................................7 6 Noninverting Attenuation .................................................................................................................8 1 SLOA058 7 Inverting Summing Circuit ...............................................................................................................9 8 Subtracting Circuit...........................................................................................................................9 9 Simulated Inductor Circuit .............................................................................................................10 10 Basic Instrumentation-Amplifier Circuit..........................................................................................11 11 Simulated Instrumentation-Amplifier Circuit...................................................................................11 12 Instrumentation Circuit With Only Two Op Amps...........................................................................12 13 Low-Pass Filter Circuits.................................................................................................................13 14 High-Pass Filter Circuits................................................................................................................14 15 All-Pass Filter Circuit.....................................................................................................................14 16 Sallen-Key Low- and High-Pass Filter Topologies.........................................................................16 17 Multiple-Feedback Topologies.......................................................................................................17 18 Single Op-Amp Twin-T Filter in Band-Pass Configuration .............................................................18 19 Single Op-Amp Twin-T Filter in Notch Configuration .....................................................................18 20 Dual-Op-Amp Twin-T Low-Pass Filter ...........................................................................................19 21 Dual-Op-Amp Twin-T High-Pass Filter ..........................................................................................19 22 Dual-Op-Amp Twin-T Notch Filter .................................................................................................20 23 Low-Pass Fliege Filter...................................................................................................................20 24 High-Pass Fliege Filter ..................................................................................................................21 25 Band-Pass Fliege Filter .................................................................................................................21 26 Notch Fliege Filter .........................................................................................................................22 27 Akerberg-Mossberg Low-Pass Filter .............................................................................................22 28 Akerberg-Mossberg High-Pass Filter.............................................................................................23 29 Akerberg-Mossberg Band-Pass Filter............................................................................................23 30 Akerberg-Mossberg Notch Filter....................................................................................................24 31 Biquad Low-Pass and Band-Pass Filter ........................................................................................24 32 State-Variable Four-Op-Amp Topology .........................................................................................25 Tables 1 Normalization Factors .....................................................................................................................8 2 A Single-Supply Op-Amp Circuit Collection SLOA058 1 Introduction There have been many excellent collections of op-amp circuits in the past, but all of them focus exclusively on split-supply circuits. Many times, the designer who has to operate a circuit from a single supply does not know how to do the conversion. Single-supply operation requires a little more care than split-supply circuits. The designer should read and understand this introductory material. 1.1 Split Supply vs Single Supply All op amps have two power pins. In most cases, they are labeled VCC+ and VCC-, but sometimes they are labeled VCC and GND. This is an attempt on the part of the data sheet author to categorize the part as a split-supply